1. Field of the Invention
The present invention relates to a printing system for executing control of printing that is performed by using a plurality of color toners and a clear toner.
2. Description of the Related Art
In an increasing number of color laser printers, special color toners, such as red and blue toners, have recently been employed in addition to known CMYK (cyan, magenta, yellow and black) toners.
Further, some color laser printers employ a special colorless toner, such as a transparent toner (hereinafter referred to as a “clear toner”), for adjustment of glossiness to provide a print with a gloss or matt finish.
A user can produce output prints having high added values by effectively using clear toner. Regarding color prints, for example, the user can perform full coat printing where the clear toner is coated over the entire print surface, or partial coat printing where the clear toner is partially coated over the print surface.
The full coat printing using the clear toner can protect the printed surface of a sheet and can give a gloss thereto by printing the clear toner over the entire surface of the sheet, which has been subjected to color printing. Also, the partial coat printing using the clear toner can be variously used to provide a partial gloss or partial decoration by partially printing the clear toner over the surface of a sheet, which has been subjected to color printing.
The partial clear toner printing can be performed by a method using a form overlay. According to that method, data for the clear toner (i.e., clear form data), which is required to perform the clear toner printing, is first registered as a form file, referred to as a clear form file, in a printing apparatus by a printer driver installed in an information processing apparatus. Then, when the clear toner printing is actually executed, a print job is sent which includes designation of the registered clear form data. Finally, when the printing apparatus prints the print job and the designated clear form data in a combined (superimposed) manner, an object contained in the clear form data is printed by using the clear toner. The partial clear toner printing can be thus realized.
However, when clear toner printing is performed by the printing apparatus, in certain instances an output print may differ from the intention of an operator, with respect to the chosen registered clear form data, because in practice the clear toner may not be coated on an image data object having a density smaller than a predetermined threshold. Image data having a value smaller than the density threshold (i.e., having a lighter color) is preferably not coated with the transparent toner (clear toner) because, for example, the clear toner coating may make little visible difference when coated on such an object.
Clear toner printing is also chargeable or billable in addition to billing for the color printing, etc. It is therefore advantageous if the operator is able to perform a test print (also called a “trial printing function”) without actually using the clear toner in the test print, for the purpose of confirming the overlapped state (position) of a glossy region and the effect (glossy- or matt expression).
Japanese Patent Laid-Open No. 2005-328257 describes a method of, in a trial copy mode for form superimposition, designating a form, designating a density of the form, and printing the form and an original document in a superimposed manner. Japanese Patent Laid-Open No. 2007-033888 describes a technique of analyzing the amount of a colorant in a process color used for input image data, and displaying information obtained with the analysis on a preview.
However, the techniques described in those patent documents have the problem that one or more the object(s) having a toner density smaller than the predetermined threshold, on which the clear toner is not coated, cannot be confirmed with respect to the form file. Further, the techniques described in those patent documents have the problem that the operability for a user is not good when the user designates for the full coat printing or the partial coat printing which uses form data.